MXPA02002567A - Heterogeneous epoxidation catalyst. - Google Patents

Abstract

Highly active and selective epoxidation catalysts are prepared by combining high surface area silica support or the like, having surface area greater than 1100 m2 g, with a titanium source. The titanium source is a non oxygenated hydrocarbon solution of a titanium halide or a vapor stream of titanium tetrachloride. The impregnated support is then calcined at an elevated temperature (preferably, in a substantially oxygen free atmosphere), and, optionally, reacted with water and or silylated. The resulting materials are highly active heterogeneous epoxidation catalysts for the reaction of olefins with organic hydroperoxides.

Description

HETEROGENIC EPOXIDATION CATALYST Field of the Invention This invention relates to a method for producing a catalyst containing titanium and its use in an epoxidation process. The catalyst is obtained by impregnating a siliceous solid of high surface area with a titanium halide in a hydrocarbon solvent, or a vapor stream of titanium tetrachloride, followed by calcination. The catalyst is highly active for olefin epoxidation.

BACKGROUND OF THE INVENTION Several different methods have been developed for the preparation of epoxides. Such a method includes the epoxidation of liquid phase of an olefin with an organic hydroperoxide in the presence of a solubilized transition metal catalyst. Despite being highly active and selective for olefin epoxidation, soluble catalysts must be recovered and recycled after being used to avoid loss in a waste stream. However, it can be very expensive to recover the soluble catalysts after use. In addition, recycling reduces catalyst productivity by also recycling certain heavy substances such as acids and polymers that tend to accumulate together with the catalyst in the heavy base stream. The heavy recycle stream reduces the epoxide selectivity or olefin conversion. Heterogeneous (insoluble) catalysts have been found. rbtl? do to avoid the disadvantages of homogeneous catalyst. The U.S. Patent No. 4,367,342 discloses an epoxidation process of olefin in the presence of an insoluble catalyst comprised of an inorganic titanium oxygen compound. Unfortunately, the described catalysts have less activity and optimum selectivity. British Patent No. 1, 332,527 teaches a process for preparing an improved titanium silica catalyst characterized by impregnating an inorganic siliceous solid with a titanium compound in an oxygen substituted hydrocarbon solvent, removing the solvent, and calcining the impregnated solid. . Suitable solvents are limited to substituted hydrocarbons of oxo and / or oxa which are liquid under ambient conditions including alcohols, ketones, ethers and esters. According to this patent, impregnation in an oxygen substituted hydrocarbon solvent produced catalysts with improved properties compared to similar catalysts prepared by other methods. The putative reason is that such catalysts have a non-agglomerated, more uniform content of titanium dioxide. A patent application filed last (EP 345, 856) describes the preparation of epoxidation catalysts which are supposed to be more active than the analogous catalysts obtained by previously known processes. EP 345,856 teaches the impregnation of silica with a gaseous stream of titanium tetrachloride, followed by calcination, hydrolysis, and, optionally, silylation. In a comparative example, a catalyst prepared by silica impregnated with a solution of tetra isopropyl ortho titanate, complexed with acetone ^? | * • - ^ __ * > . Acetyl in isopropane solvent was found to be 4.5 times less active than the catalyst prepared by vapor phase impregnation with titanium tetrachloride. Additionally, Sol. Int. PCT WO 98/50374 describes a catalyst prepared by a liquid phase impregnaoton process with a solvent that does not contain oxygen. The catalyst prepared by this method has activity similar to that produced by the method of EP 345,856. Although WO 98/50374 discloses that the higher surface area silica solids may incorporate more titanium, it does not disclose any of the benefits with higher surface area solids. New methods to produce heterogeneous catalysts for olefin epoxidation have focused on the use of high surface area, mesoporous supports such as MCM-41 and MCM-48. Methods include direct synthesis where titanium is incorporated into the support structure (see Tanev, to the. , Nature (1994) V. 368, 321) and a grafting technique in which of titanocene dichloride is grafted onto a mesoporous silica (see Maschmeyer, et al., Nature (1995) V. 378, 59). The titanocene dichloride is taught to be superior to titanium tetrachloride or titanium isopropoxide because of the lower tendency to form unwanted oligomeric titanium-oxo species. We have discovered a convenient, efficient method for producing catalyst compositions having high epoxidation (and selectivity) activity. These new catalyst compositions are significantly more active than the catalysts obtained by gf______ _ ._ ___, ___ _-_ __ ^ "___ _____, ________ _______. techniques taught in EP 345,856, WO 98/50374, or by aschmeyer, ef al.

BRIEF DESCRIPTION OF THE INVENTION The invention is an olefin epoxidation process comprising contacting an organic hydroperoxide with an olefin in the presence of a catalyst. The catalyst is produced by the method comprising: (a) impregnating an inorganic siliceous solid of high surface area having a surface area greater than 1100 m2 / g with a titanium source; (b) calcining the impregnated solid; and (c) optionally, heating the catalyst in the presence of water. The titanium source can be either a solution of a titanium halide in a non-oxygenated hydrocarbon solvent or a vapor stream of titanium tetrachloride. Optionally, the catalyst preparation method comprises the additional step of treating the catalyst with a silylating agent. We find, surprisingly, that the catalysts produced by the impregnation of siliconized solids of high surface area with titanium halides gave superior activity in olefin epoxidation compared to the known catalyst preparation methods.

DETAILED DESCRIPTION OF THE INVENTION The epoxidation process of the invention utilizes a heterogeneous catalyst containing titanium which has been found unexpectedly it gives superior epoxidation performance compared to the elaborated materials that use other methods of impregnation. In one embodiment of the invention, the catalyst preparation method is characterized by impregnating an inorganic siliceous solid of high surface area, having a surface area greater than 1 100 m2 / g, with a titanium halide solution in a solvent of non-oxygenated hydrocarbon. The solvents suitable for this purpose are those hydrocarbons that do not contain oxygen atoms, are liquid at ambient temperatures, and are capable of solubilizing the titanium halide. Generally speaking, it will be desirable to select hydrocarbon solvents where titanium halide concentrations of at least 0.5 weight percent at 25 ° C can be achieved. The hydrocarbon solvent should preferably be relatively volatile so that it can be easily removed from the inorganic siliceous solid following the impregnation. Solvents having normal boiling points of from 25 ° C to 150 ° C can advantageously be used in this manner. Particularly preferred hydrocarbon classes include C5-C12 aliphatic hydrocarbons (straight, branched, or cyclic chain), C6-C aromatic hydrocarbons? 2 (including alkyl substituted aromatic hydrocarbons), C1-C10 halogenated aliphatic hydrocarbons, and C6-C? 0 halogenated aromatic hydrocarbons. More preferably, the solvent contains no elements other than carbon, hydrogen, and (optionally) halogen. If the halogen is present in the solvent, chloride is preferred.

Mixtures of non-oxygenated hydrocarbons can be used, if desired. Preferably, the solvent used for impregnation purposes is essentially free of water (ie, anhydrous). While oxygen-containing hydrocarbons such as alcohols, ethers, esters, ketones and the like could be present in the mixture with the required non-oxygenated hydrocarbon, in a desirable embodiment of the invention only the non-oxygenated hydrocarbon is present as a solvent during the impregnation. Examples of suitable hydrocarbon solvents include n-hexane, h-heptane, cyclopentane, methyl pentanes, methyl cyclohexane, dimethyl hexanes, toluene, xylenes, methylene chloride, chloroform, dichloroethanes, chlorobenzene, benzyl chloride, and the like. Similary. Unlike the procedure described in Example I of Pat. from E. U. DO NOT. 4.021, 454, where the water is added to a mixture of titanium tetrachloride and silica in n-heptane, the process of this invention in preferred embodiment is characterized by the substantial exclusion of water until after at least the impregnation is complete and preferably until after the calcination. "Substantial exclusion" in the context of this invention means that water is not deliberately added or introduced or, if added or introduced deliberately, is removed prior to the introduction of titanium halide. The use of reagents and raw materials having water present at the normal indicia levels and usually found in such substances when sold on a commercial scale is within the scope of the present invention. Preferably, less than 500 ppm of water (more preferably, __É J_fa »___.,;., ___ tt lafa-. tStefa. ______-__ ÍE_ less than 1 00 ppm of water) occurs in the non-oxygenated hydrocarbon. Suitable titanium halides include tri- and tetra-substituted titanium complexes having one to four halide substituents with the remainder of the substituents, if any, being amino or alkoxide groups. Suitable titanium halides include tetrachloride, titanium tetrafluoride, titanium tetrabromide, titanium tetraiodide, titanium trichloride, as well as mixed halides of titanium halides Ti (11) or Ti (IV), diisopropyxytitanium dichloride, dichloride of bis (diethylamino) titanium, and the like. Preferably, all substituents attached to titanium are halide. More preferably, the titanium halide is titanium tetrachloride. While the concentration of titanium halide in the hydrocarbon solvent is not critical, the concentration of titanium halide will typically be in the range of from 0.01 mol / liter to 1.0 mol / liter. The concentration of the titanium halide in the hydrocarbon solvent and the amount of solution used is desirably adjusted to provide a titanium content in the final catalyst of from 0.1 to 15 weight percent (calculated as Ti based on the total weight of the catalyst). catalyst). Multiple impregnations, with or without intervening drying and / or calcination, can be used to achieve the desired titanium content. Inorganic siliceous solids suitable for the purpose of this invention are solid materials containing a higher proportion of silica (silica) and have a specific surface area of at least 1 100 m2 / g, and preferably the average specific surface area is 1. 1 00 m2 / ga 2000 m2 / g. The inorganic siliceous solids are porous, in them they have numerous pores, holes, or interstices throughout their structures. Synthetic inorganic oxide materials containing a higher proportion of silica comprise another class of inorganic siliceous solids. Such materials are known as refractory oxides and include silica-alumina, silica-magnesia, silica-zirconia, silica-alumina-boric and silica-alumina-magnesia. Molecular screens, particularly mesoporous or large pore molecular sieves such as MCM-41, MCM-48 and M41 S, can also be used as the inorganic siliceous solid. Preferred inorganic siliceous solids are mesoporous molecular sieves such as MCM-41, MCM-48 and M41 S. The particularly preferred is MCM-41. It is highly desirable to dry the inorganic siliceous solid prior to impregnation. Drying can be achieved, for example, by heating the inorganic siliceous solid for several hours at a temperature of 100 ° C to 700 ° C, preferably at least 200 ° C. Generally speaking, there is no need to use temperatures in excess of 700 ° C in order to achieve a sufficient degree of dryness. The vacuum or a flow stream of a dry gas such as nitrogen can be applied to accelerate the drying process. Any of the conventionally employed means for impregnating a porous solid with a soluble impregnating agent can be used. For example, the titanium halide can be dissolved in the hydrocarbon solvent and added to or otherwise combined with the inorganic siliceous solids. The inorganic siliceous solids could also be added to the hydrocarbon solution of the titanium halide. The techniques of impregnation of "incipient humidity", by means of which a minimum amount of solvent is used in order to avoid the formation of a mixture, are also suitable for use. The resulting mixture can be stabilized, optionally with stirring or another mixture, before further processing. Generally speaking, the impregnation solution should be placed in contact with the inorganic siliceous solids for a period of time sufficient for the solution to fully penetrate the available pore volume of the solids. The hydrocarbon solvent used for the impregnation can be removed from now on by drying at a moderately elevated temperature (e.g., 50 ° C to 200 ° C) and / or reduced pressure (for example, 1 mm Hg to 1 00 mm Hg) before calcination. The conditions in the solvent removal step are preferably selected such that at least 80%, more preferably at least 90%, of the hydrocarbon solvent used for the impregnation is removed before calcination. The drying step can be preceded by decanting, filtration or centrifugation to remove any excess impregnation solution. Washing the impregnated silicon solid is not necessary. Thus, a desirable embodiment of this invention is characterized by the absence of such a washing step. In another embodiment of the invention, the inorganic siliceous solid of high surface area is impregnated by a stream of ___ a ___ á * «_ a__¡ ^ HMÍ [___ J-K .. vapor of titanium tetrachloride. The vapor stream is provided by flowing a gas over liquid titanium tetrachloride. The vaporization is conducted at temperatures greater than 50 ° C at atmospheric pressure. Preferably, the vaporization temperature is greater than 80 ° C and, more preferably, greater than 1 30 ° C. Alternatively, lower temperatures are possible by reducing the reaction pressure. Preferably, the gas is an inert gas such as nitrogen, helium, argon, carbon dioxide, and the like. The vapor stream of titanium tetrachloride is thus passed over the inorganic siliceous solid of high surface area to complete the impregnation step. The silicon solid is maintained at a temperature higher than 50 ° C during impregnation. Preferably, the impregnation temperature is maintained at more than 80 ° C and, more preferably, more than 1 30 ° C. Following the impregnation, the silicon solids impregnated with liquid phase and vapor phase are burned when burned at a temperature at an elevated temperature. The calcination may be carried out in the presence of oxygen (air, for example) or, more preferably, an inert gas which is substantially free of oxygen such as nitrogen, argon, neon, helium or the like or mixture thereof. In one embodiment of the invention, the invention is first performed in a substantially free atmosphere and oxygen being introduced with oxygen thereafter. Preferably, the calcination atmosphere contains less than 1 0,000 ppm oxygen in mol. More preferably, less than 2000 ppm oxygen in mol occurs in the calcination atmosphere. Ideally, the concentration of oxygen during calcination is less than 500 ppm. It is recognized, however, that substantially oxygen-free conditions are difficult to achieve in large-scale commercial operations. Optionally, the calcination can be carried out in the presence of a reducing gas, such as carbon monoxide, when the same oxygen (for example, up to 25,000 ppm mol) is present. The optimum amount of the reducing gas, of course, will vary depending on a number of factors including the concentration of oxygen in the calcination atmosphere and the identity of the reducing gas, but reducing gas levels of from 0.1 to 10 are typically sufficient. % mol in the calcination atmosphere. In one embodiment of the invention, the calcination is carried out in an atmosphere comprised of oxygen, a reducing gas (preferably, carbon monoxide) and, optionally, one or more inert gases (eg, nitrogen, helium, argon, carbon dioxide). ). The catalyst can be maintained on a fixed platform during calcination with a gas stream passing through the catalyst platform. To improve the epoxidation activity of the catalyst, it is important that the calcination is carried out at a temperature of at least 500 ° C. More preferably, the calcination temperature is at least 700 ° C but not more than 1000 ° C. Typically, calcination times of from about 0.1 to 24 hours will be sufficient. The catalyst can be reacted with water afterwards and / or during calcination. Such reaction can be effected, for example, by contacting the catalyst with steam at an elevated temperature (preferably, a temperature in excess of 100 ° C, more preferably, a temperature in the range of 150 ° C to 650 ° C) from about 0.1 to 6 hours. Reaction with water is desirable in order to reduce the amount of residual halide in the catalyst derived from the titanium halide reagent and to increase the hydroxy density of the catalyst. The catalyst can also be treated with an organic silylating agent at elevated temperature. The epoxide selectivity is generally improved by silylation. Silylation is preferably carried out after calcination and more preferably after both calcination and reaction with water. Suitable silylation methods suitable for use in the present invention are described in the Patents of E. OR . Nos. 3, 829,392 and 3,923,843. Suitable silylating agents include organosilanes, organohalosilanes, and organodisilazanes. Organosilanes containing one to three organic substituents can be used, including, for example, chlorotrimethylsilane, dichlorodimethylsilane, nitromethyl silane, chlorotriethylsilane, chlorodimethylphenylsilane and the like. Preferred organohalosilane silylating agents include tetra-substituted silanes having 1 to 3 halo substituents selected from chlorine, bromine, and iodine with the remainder of the substituents being methyl, ethyl, phenyl, or a combination thereof. The organodisilazanes are represented by the formula R3Si-NH-SiR3, wherein the R groups are independently hydrocarbyl groups Ig ^ ^ Mg ^ g * _-.______. - ^ AéAA? 4 ^? ^ T .. ^^^ Mjl ^ 1 ^ ,, ,, ^ ,, r (preferably C! -C alkyl) or hydrogen. Substituted hexaalkyl disilazanes such as, for example, hexamethyldisilazane are especially preferred for use. The treatment with the silylating agent can be carried out either in the liquid phase (ie, when the silylating agent is applied to the catalyst as a liquid, either by itself or as a solution in a suitable solvent such as a hydrocarbon) or in the vapor phase (ie, when the silylating agent contacts the catalyst in the form of a gas). The treatment temperatures are preferably in the range of from about 80 ° C to 450 ° C, with some elevated temperatures (for example, 300 ° C to 425 ° C) generally preferred when the silylating agent is an organohalosilane and some temperatures, lower (for example, 80 ° C to 300 ° C) being preferred for organodisilazanes. The silylation can be carried out in a continuous, semi-continuous, or group manner. The length of time required for the silylating agent to react with the surface of the catalyst depends in part on the temperature and the agent employed. Lower temperatures require longer reaction times. Generally, times from 0.1 to 48 hours are suitable. The amount of the silylating agent used can vary widely. Suitable amounts of silylating agent can vary from about 1 weight percent (based on the weight of the entire catalyst composition) to about 75 weight percent, with amounts of from 2 to 50 weight percent being preferred. The silylating agent can be applied to the catalyst either in a treatment 0 a series of treatments. The catalyst composition obtained by the above described process will generally have a composition comprising from about 0. 1 to 1 5 percent (preferably, 1 to 10 percent) by weight of titanium (in the form of titanium oxide, typically, and preferably, in a high state of positive oxidation). When the catalyst has been silylated, it will also typically contain from 1 to 20 weight percent carbon in the form of organic silyl groups. Relatively lower amounts of halide (eg, up to about 5000 ppm) may also occur in the catalyst. The catalyst compositions may optionally incorporate catalyst and / or non-interference promoter substances, especially those that are chemically inert to the reagents and epoxidation products. The catalysts may contain minor amounts of promoters, for example, alkali metals (eg, sodium, potassium) or alkaline earth metals (eg, barium, calcium, magnesium) as oxides or hydroxides. Levels of alkaline earth metal and / or alkali metal from 0.1 to 5% by weight based on the total weight of the catalyst composition are typically adequate. The catalyst compositions can be employed in any convenient physical form such as, for example, powder, flakes, granules, spheres or pellets. The inorganic siliceous solid can be in such form prior to impregnation and calcination or, alternatively, converted after impregnation and / or calcination in a form to a different physical form by conventional techniques such as extrusion, pelleting, milling or the like. . The epoxidation process of the invention comprises contacting an olefin with an organic hydroperoxide in the presence of the titanium catalyst. Suitable olefins include any olefin having at least one carbon-carbon double bond, and generally from 2 to 60 carbon atoms. Preferably, the olefin is an acyclic alkene of from 3 to 10 carbon atoms such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, and isomers thereof. Also preferred are olefinically unsaturated compounds substituted with a hydroxyl group or a halogen group such as allyl chloride or allyl alcohol. The particularly preferred olefin is propylene. Preferred organic hydroperoxides are hydrocarbon hydroperoxides having from 3 to 20 carbon atoms. Tertiary and secondary hydroperoxides of from 3 to 15 carbon atoms are particularly preferred., especially secondary alkyl hydroperoxides wherein the hydroperoxy group is on a carbon atom attached directly to an aromatic ring, for example, ethylbenzene hydroperoxide. Other exemplary organic hydroperoxides suitable for use include t-butyl hydroperoxide, t-amyl hydroperoxide, cyclohexyl hydroperoxide, and eumenohydroperoxide. In such an epoxidation process, the olefin: molar ratio of hydroperoxide is not particularly critical, but it is preferable to employ a molar ratio of from 1: 1 to 20: 1. The epoxidation reaction is conducted in the liquid phase in solvents or diluents that they are liquid at the reaction temperature and pressure and are substantially inert to the reactants and products produced therefrom. In commercial practice, it will generally be more economical to use the hydrocarbon used to produce the organic hydroperoxide reagent as a solvent. For example, when ethylbenzene hydroperoxide is used, the use of ethylbenzene as the epoxidation solvent is preferred. Typically, the organic hydroperoxide is present in concentrations of from about 1 to 50 weight percent of the epoxidation reaction mixture (including olefin). Suitable reaction temperatures range from 0 ° C to 200 ° C, but preferably from 25 ° C to 150 ° C. The reaction is preferably conducted at or above atmospheric pressure. The precise pressure is not critical. The reaction mixture, for example, can be maintained substantially in a non-gaseous phase or as a two-phase (gas / liquid) system. The catalyst composition, of course, is heterogeneous in character and thus appears as a solid phase during the epoxidation process of this invention. Typical pressures vary from 1 atmosphere to 1 00 atmospheres. The epoxidation can be carried out using any of the conventional reactor configurations known in the art to react the olefin and organic hydroperoxide in the presence of an insoluble catalyst. Group or continuous procedures can be used. For example, the catalyst can be represented in the form of jJ, _______ t _____ i _-_; _____ A._Mi-_ M *? ^^^ ata ^ 1 * lA »M ^ a * p.off? tm¡ & or fixed mixture with conditions being elaborated for the removal of heat generated as a result of the exothermic epoxidation reaction. A fixed platform catalytic reactor adaptable for use with the present process is described in EP 323,663. When the epoxidation has proceeded to the desired degree, the product mixture is separated and the products (epoxide and alcohol derived from the organic hydroperoxide) are recovered by conventional methods such as fractional distillation, selective extraction, filtration, and the like. The reaction solvent, the catalyst composition, and any unreacted olefin or organic hydroperoxide are recycled for further use. The following examples merely illustrate the invention. Those skilled in the art will recognize various variations that are within the spirit of the invention and scope of the claims. EXAMPLE 1: PREPARATION OF CATALYST ACCORDING TO THE INVENTION The silica support MCM-41 can be made according to any known literature procedure. See, for example, Pat. from E. U. NO. 3,556,725, DiRenzo, eí al. , Microporous Materials (1 997), Vol. 10, 283, or Edler, e al. , J. Chem. Soc, Chem. Comm. (1 995), 1 55. The obtained MCM-41 gel is calcined at 550 ° C for 14 hours before use. Catalyst 1 A: MCM-41 (4.36 g, BET surface area is 1488 m2 / g) is placed in a 500 mL 3-necked round bottom flask equipped with an inert gas inlet, an outlet, and a scrubber contains solution of aqueous sodium hydroxide. A solution of titanium tetrachloride (IV) (0.55 mL, 0.95 g of TÍCI4 and 60 g n-heptane, 99 +%, water <50 ppm) is added to the MCM-41 under dry inert gas atmosphere. The mixture mixes well when swirled and the solvent is removed by roto-evaporation under vacuum at 80 ° C. The impregnated material above is loaded into a tubular quartz reactor (1 inch ID, 16 inches long) equipped with a thermocavity, a 500 mL 3-neck round base flask, a heating cap, an inert gas inlet , and a scrubber (which contains sodium hydroxide solution). The catalyst platform is heated to 850 ° C under a flow of 400 cc / min of dry nitrogen (99.999%) for 30 minutes before cooling to 400 ° C. The water (3.0 g) is thus added to the 3-neck round base flask and the flask is heated with a heating cap to reflux under a flow of 400 cc / min of nitrogen in order to distill the water through the platform of catalyst over a period of 30 minutes. A hot air gun is used to heat the round base flask to drive any residual water through the platform. The platform is thus maintained at 400 ° C for an additional 2 hours before cooling to room temperature. The unsymilized Ti / MCM-41 catalyst (3.72 g) is added to a 500 mL 3-necked round bottom flask equipped with a condenser, a thermometer, and an inert gas inlet. Hexamethyldisilazane (0.96 g) in heptane (36 g, water <50 ppm) is added to Ti / MCM-41 and the system is heated in an oil group (1 15 ° C) to reflux (98 ° C) under inert atmosphere for 2 hours before cooling to The catalyst is filtered and dried thus under flow of .5 hours. The measured Ti load of the catalyst is 5.0% by weight. Catalyst 1 B: The silica MCM-41 (4.0 g, BET surface area is 1 140 m2 / g) is loaded in a tubular quartz reactor (1 inch ID, 16 inches long) equipped with a thermocavity, a flask of 3-round round base of 500 mL, a heating cap, an inert gas inlet, and a scrubber (containing sodium hydroxide solution). The catalyst platform is heated to 400 ° C under dry nitrogen (99.999%) flow (400 cc / min). The water (1.0 g) is thus added to the 3-neck round base flask and the flask is heated with a heating cap to reflux under 400 cc / min of nitrogen flow in order to distill the water through the catalyst platform for a period of 30 minutes A hot air gun is used to heat the round base flask to drive any residual water through the platform. The platform is thus cooled to 300 ° C. The titanium tetrachloride (3.29 g) is transferred to the 3-neck round-bottomed flask and the flask is heated with a reflux of heating cap under 400 cc / min of nitrogen flow in order to distill the TiCl4 through the platform of catalyst over a period of 1 hour. A hot air gun is used to heat the round base flask to drive any residual TiCI through the platform. The platform is heated to 700 ° C for 0.5 hours before cooling to 400 ° C. The water (1.0 g) is thus added to the base flask r ## 3-neck wave and the flask is heated with a heating cap to reflux under 400 cc / min of nitrogen flow in order to distill the water through the catalyst platform for a period of 30 minutes. A hot air gun is used to heat the round base flask to drive any waste water through the platform before cooling to room temperature. The silylation of the non-silylated Ti / MCM-41 catalyst is carried out according to the procedure of Catalyst 1 A. The measured Ti loading of the catalyst is 4.9% by weight.

COMPARATIVE EXAMPLE 2: PREPARATION OF CATALYST ACCORDING TO WO 98/50374 Comparative Catalyst 2A: The silica support (Grace Davison DAVICAT P-732, particle size 0.6-1 .4 mm, surface area 300 m2 / g) is dried at 500 ° C in air for 2 hours before cooling to room temperature. The dried silica (162 g) is placed in a 500 mL 3-necked round bottom flask equipped with an inert gas inlet, a gas outlet, and a scrubber containing aqueous sodium hydroxide solution. A solution of titanium (IV) tetrachloride (1 1 .75 mL, 20.32 g of TiCl 4 and 252 g n-heptane, 99 +%, water <50 ppm) is added to the silica under a dry inert gas atmosphere. The mixture mixes well when swirled and the solvent is removed by roto-evaporation under vacuum at 80 ° C. One part (35 g) of the previous impregnated material is loaded into a tubular quartz reactor (1 inch ID, 16 inches long) 1f pfffr ** > > * t * ^ «^ + < *** - > ™ •? -? A ____? .___ á Ai equipped with a thermocavity, a 500 mL 3-necked round base flask, a heating cap, an inert gas inlet, and a scrubber (containing sodium hydroxide solution) The catalyst platform is heated to 850 ° C under a flow of 400 cc / min of dry nitrogen (99.999%) for 30 minutes before cooling to 400 ° C. The water (3.0 g) is thus added to the flask. 3-round round base and the flask is heated with a heating cap to reflux under flow of 400 cc / min of nitrogen in order to distill the water through the catalyst platform for a period of 30 minutes. of hot air to heat the round base flask to conduct any waste water through the platform.The platform is thus kept at 400 ° C for an additional 2 hours before cooling to room temperature.The catalyst Ti / silica not silylated in a 3-neck round bottom flask 500 mL equipped with a condenser, a thermometer, and an inert gas inlet. The hexamethyldisilazane (6.0 g) in heptane (76 g, water <50 ppm) is added to the Ti / silica and the system is heated in an oil group (1 15 ° C) to reflux (98 ° C) under inert atmosphere for 2 hours before cooling to room temperature. The catalyst is filtered, washed with 1 00 mL of heptane, and then dried under inert gas flow at 180-200 ° C for 2 hours. The measured Ti load of the catalyst is 2.97% by weight. Comparative Catalyst 2B: The silica support (Grace Davison DAVICAT P-732, particle size 0.6-1.4 mm, surface area 300 m2 / g) is dried at 400 ° C in dare for 4 hours before cooling to temperature ambient. The dried silica (177 g) is placed in a 500 mL 3-necked round base flask equipped with an inert gas inlet, a gas outlet, and a scrubber containing aqueous sodium hydroxide solution. A solution of titanium (IV) tetrachloride (1 9 mL, 32.87 g of TÍCI4 in 262 g n-heptane, 99 +%, water <50 ppm) is added to the silica under a dry inert gas atmosphere. The mixture mixes well when swirled and the solvent is removed by roto-evaporation under vacuum at 80 ° C. The rest of the process is the same as the catalyst preparation 3. The Ti load of the catalyst is 3.2% by weight. Comparative Catalyst 2C: The silica support (Grace Davison DAVICAT P-732, particle size 0.6-1.4 mm, surface area 300 m2 / g) is dried at 300 ° C in air for 4 hours before cooling to room temperature ambient. The dried silica (168 g) is placed in a 500 mL 3-necked round bottom flask equipped with an inert gas inlet, a gas outlet, and a scrubber containing aqueous sodium hydroxide solution. A solution of titanium (IV) tetrachloride (1 8.2 mL, 31.5 g of TiCl4 in 252 g n-heptane, 99 +%>, water <50 ppm) is added to the silica under a dry inert gas atmosphere. The mixture mixes well when swirled and the solvent is removed by roto-evaporation under vacuum at 80 ° C. The rest of the process is the same as the Catalyst 3 preparation. The measured Ti load of the catalyst is 4.2% by weight.

COMPARATIVE EXAMPLE 3: PREPARATION OF CATALYST OF lf ^ ff l f8 ^ - -__-_-._-._ AGREEMENT TO EP 345,856 Comparative Catalyst 3A: The silica support (Grace Davison DAVICAT P-732, particle size 0.6-1 .4 mm, area of surface 300 m2 / g) is dried at 450 ° C in air for 2 hours before cooling to room temperature. The dried silica (37 g) is placed in a tubular quartz reactor (1 inch ID, 16 inches long) equipped with a thermocavity, a 500 ml 3-necked round bottom flask, a heating cap, an inlet of inert gas, and a scrubber (containing sodium hydroxide solution) The catalyst platform is heated to 200 ° C under dry nitrogen (99.999%) flow (400 cc / min). Titanium tetrachloride (1 9 g) is thus added to the 3-necked round bottom flask and the flask is heated with a heating cap to reflux under 400 cc / min of nitrogen flow in order to distill the TiCl through of the catalyst platform for a period of 1 hour. A hot air gun is used to heat the round base flask to drive any residual TiCl4 through the platform. The platform is then heated to 600 ° C and maintained at 600 ° C for 2 hours before cooling to 300 ° C. The water (3.0 g) is thus added to the 3-neck round base flask and the flask is heated with a heating cap to reflux under a flow of 400 cc / min of nitrogen in order to distill the water through the platform of catalyst over a period of 30 minutes. A hot air gun is used to heat the round base flask to conduct any waste water through the platform before cooling to 200 ° C. The hexamethyldisilazane (4.0 g) is then added to the 3-necked round base flask and the flask is heated with a HF cap to reheat under 400 cc / min of nitrogen flow in order to distill the hexamethyldisilazane through the platform of catalyst over a period of 1 hour. A hot air gun is used to heat the round base flask to drive any residual hexamethyldisilazane through the platform before cooling to room temperature. The catalyst contained 3.0% by weight of Ti. The silica support (Grace Davison DAVICAT P-732, particle size 0.6-1.4 mm, surface area 300 m2 / g) is dried at 450 ° C in air for 2 hours before cooling to room temperature. The dried silica (36 g) is placed in a tubular quartz reactor (1 inch ID, 16 inches long) equipped with a thermocavity, a 3-necked 500-mL round bottom flask, a heating cap, a inert gas inlet, and a scrubber (containing sodium hydroxide solution). The catalyst platform is heated to 300 ° C under dry nitrogen (99.999%) flow (400 cc / min). The titanium tetrachloride (7.4 g) is thus added to the 3-neck round-bottomed flask and the flask is heated with a heating cap to reflux under 400 cc / min of nitrogen flow in order to distill the TiCl4 through the the catalyst platform for a period of 1 hour. A hot air gun is used to heat the round base flask to drive any residual TiC through the platform. The platform is then heated to 850 ° C and maintained at 850 ° C for 0.5 hours before cooling to 400 ° C. The water (3.0 g) is thus added to the 3-neck round base flask and the flask is heated with a heating cap to reflux under a flow of 400 cc / min of nitrogen in order to distill the water through the platform of catalyst over a period of 30 minutes. A hot air gun is used to heat the round base flask to conduct any waste water through the platform before cooling to room temperature. The non-silylated Ti / silica catalyst (15 g) is added to a 500 mL 3-necked round bottom flask equipped with a condenser, a thermometer, and an inert gas inlet. The hexamethyldisilazane (3.0 g) in heptane (43 g, water <50 ppm) is added to the Ti / silica and the system is heated in a group of oil (1 1 5 CC) to reflux (98 ° C) under an inert atmosphere. 2 hours before cooling to room temperature. The catalyst is then filtered and dried under inert gas flow at 1 80 ° C for 1 hour. The measured Ti load of the catalyst is 2.6% by weight.

COMPARATIVE EXAMPLE 4: CATALYST PREPARATION USING TITANIUM ISOPROPOXID PRECURSOR AND SUPPORT MCM-41 Comparative Catalyst 4A: The MCM-41 gel is pyrolyzed at 550 ° C under nitrogen flow and then calcined in air for 14 hours at 550 ° C. The BET surface area of the material is 1 1 00 m2 / g. The MCM-41 (2.42 g) is placed in a 500 mL 3-necked round bottom flask equipped with an inert gas inlet and a gas outlet. A solution of titanium (IV) diisopropoxide bis (acetylacetonate) (0.74 g of 75% Ti ('OPr) 2 (acac) 2 in 39.7 g of anhydrous isopropanol) is added to the MCM-41 under dry inert gas atmosphere . The mixture mixes well and the solvent is removed by removing the nitrogen at 100 ° C. The catalyst is calcined at 800 ° C in air for 2 hours. The non-silylated Ti / silica catalyst is added to a 500 mL 3-necked round bottom flask equipped with a condenser, a thermometer, and an inert gas inlet. The hexamethyldisilazane (1.5 g) in heptane (43 g, water <50 ppm) is added to the Ti / silica and the system is heated in an oil group (1 15 ° C) to reflux (98 ° C) under Inert atmosphere for 2 hours before cooling to room temperature. The catalyst is then filtered and dried under inert gas flow at 180 ° C for 1 hour. The measured Ti load of the catalyst is 2.6% by weight. Comparative Catalyst 4B: The MCM-41 gel is pyrolyzed at 550 ° C under nitrogen flow and then calcined in air for 14 hours at 550 ° C. The surface area BET of the material is 1 100 m2 / g. The MCM-41 (2.42 g) is placed in a 500 mL 3-necked round bottom flask equipped with an inert gas inlet and a gas outlet. A solution of titanium (IV) diisopropoxide bis (acetylacetonate) (1.22 g of 75% Ti ('OPr) 2 (acac) 2 in 39.5 g of anhydrous isopropanol) is added to the MCM-41 under the atmosphere of dry inert gas. The mixture mixes well and the solvent is removed by removing the nitrogen at 100 ° C. The catalyst is calcined at 800 ° C in air for 2 hours. Silylation of the non-silylated Ti / MCM-41 catalyst is carried out according to the procedure of Comparative Catalyst 4A. The load of The catalyst size is 4.0% by weight.

COMPARATIVE EXAMPLE 5: PREPARATION OF CATALYST ACCORDING TO MASCHMEYER, ET. TO THE. ^ Comparative Catalyst 5: This example demonstrates, for comparative purposes, the preparation of a catalyst of a titanocene dichloride precursor according to the methods of Maschmeyer et al. , Nature (1,995) V. 378, 1 59. The titanocene dichloride (3 15 g) is weighed into a 250 ml flask and 142 g of dry dichloromethane (Aldrich, anhydrous) is added. The flask swirls vigorously. The silica support MCM-41 (surface area 1252 m2 / g) is thus added to the above mixture and the mixture is stirred for 30 minutes. The triethylamine (5.1 g) is added to the mixture and stirred for an additional 2 hours. The reaction mixture is filtered and the filter layer washed with dichloromethane (3x80 ml). The solid is packed into a tube reactor (1 inch ID) equipped with a thermocavity, a 500 ml 3-neck round bottom flask, a heating cap, an inert gas inlet, and a scrubber. The catalyst platform is heated to 200 ° C under dry nitrogen (99.999%) flow (400 cc / min) and the material is dried for 1 hour. Then the catalyst platform is heated to 500 ° C under air flow (400 cc / min) and calcined under air flow for 2 hours. Silylation of the non-silylated Ti / MCM-1 catalyst is carried out according to the procedure of Comparative Catalyst 4A. The measured Ti load of the catalyst is 8.5% by weight.

EXAMPLE 6: GROUP EPOXIDATION OF 1 -OCTENE WITH OXIDATE L * -ill-_ _ ___- ^. J _ «» ____ ^ _ EBHP At 50 ° C To evaluate the performance of the catalysts prepared in Example 1 and Comparative Examples 2-5, epoxidations were carried out in a group of 1-octene using ethylbenzene hydroperoxide. The following procedure is used. A feeding solution is prepared by mixing 220 g of 1-octene, 50 g of oxidative EBHP, and 10 g of nonane (internal standard). A part of the feed solution (28 g) is transferred under an inert atmosphere to a 1 00 mL 4-neck round base flask attached to a condenser, a thermocouple, a stirring rod, and a sample port. The mixture is heated to 50 ° C, while stirring (with a stirring rod) at a speed of 700 rpm. A catalyst of Ti / MCM-41 or Ti / silica (powder, 0.2 g) is thus added to the flask and the mixture is heated for 30 minutes at 50 ° C. A sample of product (3 mL) is taken 30 minutes after the catalyst addition. Both the feed sample and the product sample are analyzed by GC for EBH P and epoxyoctane concentrations. Epoxide conversion and selectivity are calculated in relation to the hydroperoxide consumed. The first order of activity (k) is calculated by the equation k = [In (1 -% conversion)]. These results, in Table 1, show that the use of high surface area supports leads to an unexpected increase in activity 2-4 times before catalyst preparations on silica (WO 98/50374 or EP 345,856) or MCM-41 (Maschemeyer, et al.). Also, the vapor phase and liquid phase impregnation of MCM-41 results in equivalent catalyst activity.

TABLE 1: COMPARISON OF CATALYST ACTIVITY.

Comparative example

Claims (1)

1. CLAIMS ^ 1. An epoxidation process comprising contacting an organic bidroperoxide with an olefin in the presence of a catalyst obtained by a method comprising the steps of: (a) impregnating an inorganic siliceous solid with a titanium source selected from the group consisting of: 1) a solution of a titanium halide in a non-oxygenated hydrocarbon solvent; and (2) a vapor stream of titanium tetrachloride; said inorganic siliceous solid having a surface area greater than 1 100 m2 / g; (b) calcining the impregnated silicon solid to form the catalyst composition; and (c) optionally, heating the catalyst in the presence of water; said method being characterized by the substantial exclusion of water until after step (a) is complete. 2. The epoxidation process according to claim 1, characterized in that the titanium halide is titanium tetrachloride. 3. The epoxidation process according to claim 1, characterized in that the impregnation step (a) (1) is achieved by combining a solution of the titanium halide in the non-oxygenated hydrocarbon solvent with the inorganic siliceous solid and by stirring therefrom. hereafter the hydrocarbon solvent. 4. The epoxidation process according to claim 1, Characterized because the inorganic siliceous solid is MCM-41. 5. The epoxidation process according to claim 1, characterized in that the non-oxygenated hydrocarbon solvent is selected from the group consisting of C5-C12 aliphatic hydrocarbons, C6-C2 aromatic hydrocarbons, Ci-C10 halogenated aliphatic hydrocarbons, halogenated aromatic hydrocarbons. Ce-Cío and mixtures thereof. 6. The epoxidation process according to claim 1, characterized in that the water is substantially excluded until after step (b) is completed. The epoxidation process according to claim 1, characterized in that the method for obtaining the catalyst comprises an additional step after step (c) to treat the catalyst with a silylating agent. 8. The epoxidation process according to claim 7, characterized in that the silylating agent is selected from the group consisting of organosilanes, organohalosilanes, organodisilazanes, and mixtures thereof. 9. The epoxidation process according to claim 1, characterized in that the calcining step (b) is carried out at a temperature of at least 500 ° C. 10. The epoxidation process according to claim 1, characterized in that the organic hydroperoxide is ethylbenzene hydroperoxide or t-butyl hydroperoxide. eleven . The epoxidation process according to claim 1, characterized in that the olefin is a C3-C10 acyclic alkene. 12. The epoxidation process according to claim 1, characterized in that step (b) is carried out in an atmosphere substantially free of oxygen. 3. The epoxidation process according to claim 1, characterized in that step (b) is carried out in an oxygen-containing atmosphere and a reducing gas. A method for preparing a catalyst comprising the steps of: (a) impregnating an inorganic siliceous solid with a titanium source selected from the group consisting of: (1) a solution of a titanium halide in a hydrocarbon solvent not oxygenated; and (2) a vapor stream of titanium tetrachloride; said inorganic siliceous solid having a surface area greater than 1 100 m2 / g; (b) calcining the impregnated silicon solid to form a calcined catalyst precursor; and at least one of steps (c) or (d); (c) heating the calcined catalyst precursor in the presence of water; or (d) treating the calcined catalyst precursor with a silylating agent; said method being characterized by the substantial exclusion of water until after at least the stage (a) is completed. 15. The method according to claim 14, characterized in that the titanium halide is titanium tetrachloride. 1 6. The method according to claim 14, characterized in that step (b) is carried out in an atmosphere substantially free of oxygen. The method according to claim 14, characterized in that the impregnation step (a) (1) is achieved by combining a solution of the titanium halide in the non-oxygenated hydrocarbon solvent with the inorganic siliceous solid and by stirring therefrom. forward the hydrocarbon solvent. The method according to claim 14, characterized in that the inorganic siliceous solid is MCM-41. The method according to claim 14, characterized in that step (b) is carried out in the substantial absence of water. The method according to claim 14, characterized in that step (b) is carried out at a temperature of at least 500 ° C. twenty-one . A method for preparing a catalyst comprising the steps of: (a) forming a mixture by combining a solution of titanium tetrachloride in a hydrocarbon solvent selected from the group consisting of C5-C16 aliphatic hydrocarbons, C6-C aromatic hydrocarbons? 2, halogenated aliphatic hydrocarbons d-C10, halogenated aromatic hydrocarbons C6-C? 0 and mixtures ; I MÜÜ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ (b) removing the hydrocarbon solvent from the mixture to produce an impregnated MCM-41; (c) calcining the impregnated MCM-41 at a temperature of from 700 ° C to 1000 ° C to form a calcined catalyst precursor; (d) heating the calcined catalyst precursor in the presence of water; and (e) treating the calcined catalyst precursor with a silylating agent; said method being characterized by the substantial exclusion of water until after step (c) is complete. 22. The method according to claim 21, characterized in that step (c) is carried out in an atmosphere substantially free of oxygen. 23. The method according to claim 21, characterized in that step (c) is carried out in an atmosphere comprised of oxygen and a reducing gas. The method according to claim 21, characterized in that the reducing gas is carbon monoxide. 25. The method according to claim 21 comprising a further step before step (a) to dry the MCM-41. __ * __, *.